In Chico, an accessory dwelling unit (ADU) is a complete, independent living unit on the same lot as a main home. The City lets one detached ADU and one junior ADU (JADU, up to 500 square feet, inside the existing house) go on a lot with an existing single-family home, and it offers 14 pre-approved ADU plans free of charge. Confirm size and setback rules with the Planning Division before you buy or build.
What is an ADU?
The City describes an ADU as an attached or detached residential unit with complete independent living facilities on the same parcel as the main home. It can be an efficiency unit or a manufactured home. A JADU is no more than 500 square feet and sits entirely inside an existing single-family residence, with its own or shared sanitation facilities.
What is allowed on a lot?
One detached ADU and one JADU may be permitted on a lot with an existing single-family home. ADUs may be permitted on lots with an existing or proposed single or multi-family dwelling. Size, setbacks and design requirements are in the City's ADU Development Standards, so read those or call Planning at (530) 879-6800 or zoning@chicoca.gov before you rely on a number.
What are the permit steps?
- Confirm eligibility with the Planning Division.
- Review the Chico ADU Development Standards for size, placement and design.
- Prepare building plans, a site plan and an Erosion Control and Sedimentation Plan, then apply for building and sewer connection permits through the Building Division.
- If the property is on septic or a well, contact Butte County Environmental Health at (530) 552-3880.
Are there free plans?
Yes. The City offers 14 pre-approved ADU plans free of charge, prepared by Jacksons & Sands Engineering, which also completes energy calculations during construction at no cost. Site plan and erosion control services from that firm are available for a fee. Permit fees are in the City's current Master Fee Schedule.
What should buyers check?
If a home already has a garage conversion or an extra unit, ask for permits. Unpermitted work can create problems at inspection, appraisal and resale. Adding an ADU can change your property tax reassessment and your insurance, so ask your insurer and review the property tax guide. California rules on ADUs change often, so talk with the City before you commit.
Frequently Asked Questions
What is a JADU?
A junior ADU of up to 500 square feet built inside an existing single-family home.
How many ADUs can I add to a lot in Chico?
One detached ADU and one JADU may be permitted on a lot with an existing single-family home, per the City.
Does Chico offer ADU plans?
Yes. The City offers 14 pre-approved plans free of charge.
Who do I call about ADU rules?
The City Planning Division at (530) 879-6800 or zoning@chicoca.gov.
General information, not legal advice. State ADU law changes often and the City's page does not list every size and setback rule, so confirm with the City before you buy or build. Questions? Call or text me at 707-672-6549. Happy to help.
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